Quenching oils



Patented Aug. 11, 1931 UNI Tao STATES PATENT OFFICE HUGH ,RODMAN, or onxmoivr, rnNusYIJvANIA, 'nssxeivon rononmn onnmrcsn 'comrmvnor'vnnomi, rEuNsYLvAn1A, CORPORATION, or rmmsrnvanm QUENCHING- one No Drawing.

creasethe initial uenching speed of certain mineral oils, particularly those of low viscosity and low flash point by the addition thereto of a smallamount of other material,

without materially increasing the total cost. In Patent No. 1,535,379 there is disclosed a methodof increasing the initial quenching sp eedof low-viscosity low-flash mineral'oils by adding thereto a small amount of highpass off in distilling processes.

viscosity high-flash mineral oil. The present invention is an impro'vemfiit upo'nfithat described in the patent,- andis predicated upon scribed in the patent may be improved upon and more economically obtained by adding to.

mineralquenching oils of low viscosity and low flash point, a small amount ofthe residu-- um obtained in the distillation of certain high-viscosity high-flash mineral oils, and

particularly the residuum obtained when such oils are distilled in vacuo. -The result' ing accelerated ifiitial quenching effect of the treated oil is apparently dueto some substances in the added residuum that does no The term residuum is here usedto denote the solid or semi-solid tacky substance left in the stills after distilling off all material which can properly be called oil. The

term is not to be confused with the term residual oil, which means the oily residue left in the stills after distilling off any portion of the original charge. Theresiduums here referred to are the residues left in'the stills after distilling ofl or destroying the oily portion of the charge but without carrying the distillation to the point of producing coke. They are heavy, tacky, dark green or black substances, solid or semi-solid at room tem-- perature and are used for road building and the like'not for lubrication.

' In the quenching' -of steel the arthas generally used-a mineral oil bath having low v1scosity,iI e. a viscosity of not over 150 seconds at 100 F. on a- Saybolt v iscosimeter,

. "just above referredto.

Application filed may 16, 15129.- Serial No. 303,716.

and a flash point of from 300 to 450 measured by the Cleveland cup method. Low-viscosity oil is preferred forquenching becausethe lower the viscosity the-less of it adheres to the steel-parts upon removal from 55v the bath, consequently there is less .waste from drippage, and also oils of low vi'scosity are generally believed to give more rapid 1 cooling of the steel than those of high vis cosity. But since, the coo-ling bath is un- 0 avoidably heated to a hightemperature y' the hot-steel immersed in it, oils for such us s must have a sufliciently high flashpoint to avoid ignition, and a workable flash point has largely determined the viscositycharactere5 istic; viscosity normally rising -with flash point. i the further discoverythat the. results de- In quenching steel for most. purposes it is desirable to cool it rapidly through its critical temperature, and thereafter at a slower rate.- Water uenches quite rapidly and is desirablein t at respect, but it has the disadvantage that the cooling, rate is too rapid at lower steel. temperatures. Oil, however,

hasa markedly decelerating rate ofv cooling,

and for steel below 700 F. -The cooling curve tends to flatten out. That is, the rate of cooling is materially slower than at higher temperatures, 011 quenching improves the 7 physical characteristics of the steelffor most uses, and it is because of this advantage that oil is used in spite of its relatively greater expenseas compared to water. But in the initial stage of quenching the relatively slo cooling effect of the oil bath is not an ad- 8 A vantage, Mineral oil baths have been imi proved to a slight extent by iricreasing their initial quenching rate by addition of animal oils, but these are relatively expensive, and

therefore materially increase. the cost of, "quenching oil so treated or blended.

The present nventlon provides a simple and inexpensive way of increasing. the initial quenching speeds of low-viscosity oil, with-; out changing the desirable I' have discovered that the residuums ob v tained from the distillation of mineral oils are much more 'eflective for increasing the initial quenchingspeedof'low-viscosity low characteristics I 20 is added.

,flash mineral oils than are much greater quantities of high-viscosity high-flash mineral oils themselves. I have 'found that apparently the element which increases the initial quenching speed of oils does not pass over by distillation, butremains in the residuum of such a process. The residuum from the vacuum process oi distilling oils are black or .dark green products, tacky, usually solid at room temperature, and they are completely and permanently soluble in low viscosity 'mineral oils. In addition they are very cheap, being in effect a waste product of oil .distillation. A comparatively small quantity of such residuum added to quenching oiloflow viscosity low flash point will greatly increase its initial quenching rate, without increasing the cost of the compound ascompared to the base oil to which the residuum 'I have found that the addition oi of the solid residuum of vacuum distillation of mineral oils tothe usual low-viscosity lowflash mineral quenching oils as a base, raises an the viscosity of the mixture only slightly, but produces-an oil having a higher initial quenching rate for red hot steel than can be produced by adding twice as much high-viscosity high-flash oil as described in Patent 1,535,379, and much more than by adding the usual quantities of animal or vegetable oils. Moreover the saidresiduum is courpletely and permanently soluble in the lowviscosity quenching oil, whereas the steam refined cylinder stock referred ,to in the patent shows a tendency. to settle out upon long standing. The residuum product is cheaper, and since comparatively a half or less in quantity may be used, the expense of treating the base quenching oil by the present process is cheaper thanthat described -in the said patent.

It appears probable, from mv experiments and discoveries, that the substance which is efiective in increasing the initial quenching rate of low-viscosity mineral oils is not mere- 1y a mineral oil of high viscosity. and high flash point, but rather some substance which is in the accumulated residuum left by the petroleum distillation process. Consequently the more concentrated by distillation the residuumis, the more quantatively efiective it appears to be for raising the initial quenchfing rate of thebase oil to which it is-to be added. Apparently the effective constituent does not pass over with the distillate. While the residuum products of atmosthe process, and armaterial improvement of the product, due to the increased initial quenching rate and more complete solubility of the residuum product, and stability of the union thereof with thelow-viscosity quenching oil.

I claim:

1. A quenching oil comprisin a low-viscosity' mineral oil combined wlth a lesser amount of the non-liquid residuum resulting fromdistillation of a mineral oil.

Z'Aquenching oil comprisin a low-viscosity mineral oil combined with a lesser amount of the residuum resulting from distillation of a mineral oil in vacuo.

3. A quenching oil comprising a base of low-viscosity low-flash mineral oil with a smaller amount of the non-liquid. residuum resulting from distilling mineral oil in vacuo dissolved in said base.

4. The method of increasing the initial quenching speed of a low-flash low-viscosity mineral oilgpconsisting in combining therewith a smaller amount of the residuum product resulting from distillation of a mineral J 5. The -method of increasing the initial quenching speed of a low-flash low-viscosity mineral oil, consisting indissolvin therein a smaller amount of the solid 'resi uum resulting from distilling a mineral oil in vacuo.

, In testimony whereof,Isign my name. i

- HUGH RODMAN.

pherie distillationei oil have a considerable substantial amount of tar which is includedin such residuum. Tar sinks to the bottom of 

